"social" features

[Robert Jäschke]

• Show every logged in user on /user/OTHERUSER some information about their connection, i.e., "OTHERUSER is your friend" or "OTHERUSER is also member of groups X, Y, and Z" (with corresponding hypderlinks, of course).

• Add some icons for friends, etc. which could be shown there.

[Thomas Niebler]

Only "common groups" is missing, as I see it. Minor importance.

[Mario Holtmüller]

I pushed the implementation of this into the newgroups branch. It is NOT working as intended so far. The reason is, that the groupMembership lists only contain the user itself but nothing else

[Mario Holtmüller]

Resolved the "problem".